(1) Field of the Invention
This invention relates to a device for the distribution of firing pulses, a circuit arrangement for sequence control of power regulators with such a device for distribution of firing pulses and a process for the sequence control of power regulators for operation with such a circuit arrangement.
(2) Description of Related Art
In various utility model documents and publications of patent applications by AEG Power Solutions B.V., AEG Power Solutions GmbH, AEG Power Supply Systems GmbH, power supply assemblies with power regulators are known that are operated with a sequence control—also as a voltage sequence control. Moreover the book “Thyristorized Power Controllers” by G. K. Dubey, S. R. Doradla, A. Joshi and R. M. K. Sinha, ISBN 978-0-85226-190-3 describes such power supply assemblies.
In the case of a power supply assembly with power regulators operated with sequence control, there is generally a transformer that has several secondary taps. Each of these taps is linked with a power regulator input. The outputs from the power regulator are merged in a bus bar. The bus bar is linked with an output of the power supply assembly. A voltage is created between the output of the power supply assembly and a reference potential. whose effective value is set by at least one power regulator, frequently however by two power regulators.
Using phase control, the effective value of the voltage can be adjusted at the output of each power regulator. Because of the connection between the power regulator inputs with various secondary transformer taps, the effective values of the maximum voltages at the power regulator output differ. Theoretically it is possible to set voltages in the entire voltage range between 0 V and the maximum voltage with the power regulator whose inlet is connected to the transformer tap, in which the maximum voltage is provided. In practice however this runs into difficulties. Moreover, high voltage jumps are obtained, leading to excessive harmonics, reducing the power factor of the power supply assembly. For this reason, with sequence control for setting a voltage between the voltage levels of two transformer taps, one power regulator is switched through during the complete half-wave of the network voltage, while the other power regulator, according to a control angle is operated with phase angle control. Thus, two power regulators are very often operated with this type of power supply.
With the previously-known power supply assemblies, every power regulator is allocated a device for the generation of a firing pulse. Each device for the generation of the firing pulse is connected with a control and/or regulator. The power regulators that have to be operated in order to set this voltage are determined in the controller and/or regulator according to the voltage desired. The control angle that has to be set by the power regulator, which is connected on the input side with the higher voltage potential, is also determined here
As only two power regulators are generally operated in the case of a power supply assembly with power regulators operated in sequence control, a number of components, in particular a number of the devices for the generation of firing pulses, are unused during the operation of such a power supply assembly.
The connection between the controller and/or regulator and the device for the generation of the firing pulses is via a bus. A frequently-used bus has a bandwidth of 16 bits, i.e. data words with a width of 16 bits, can be transmitted. With a data word sent via the bus it is also possible to show—or as often termed—address 216 different statuses. This was used in the past such that each power regulator of the power supply assembly was allocated a section in the addressable space. Each status in a section of the addressable space was also allocated a control angle. If a data word was given by the controller and/or regulator to the bus, the control angle to be set for all power regulators was given to the bus simultaneously. The section of the data word containing the information for the control angle of the downstream power regulator was evaluated in every device for the generation of firing pulses.
This manner of transmitting the control angle information meant that, for example, a total of 65536 statuses could be shown with a word width of 16 bits. In a power supply assembly with four power regulators, each power regulator is allocated a section of 4 bits. It is possible to allocate each power regulator 24=16 statuses. If the adjustable control angle lies between 0 and 180°, a resolution of 181°:16=11,313° is possible. The resolution is better for larger and more realistic word widths. The example shows, however, how the resolution can be determined. The resolution worsens when the power supply assembly has more power regulators. A large number of power regulators may be necessary, however, if large voltage swings are to be set. A large number of power regulators can also be advantageous if the output factor is to be increased. The voltage swings then realized by each individual power regulator can be reduced by a large number of power regulators. The proportion of the harmonics can be reduced, as the voltage range covered by the individual power regulators becomes smaller.
This is the basis for this invention.